This invention relates to cellular telephone communications test and in particular to a radio frequency (RF) test set having a concurrent measurement architecture.
RF devices include a wide variety of two way radios, pagers, satellite terminals, wireless local area networks (LANs) and other communications devices that use radio or lightwave frequencies. All such RF devices share a common problem of relatively complex, slow, and expensive tests that are typically performed during the manufacturing and maintenance of the equipment. The high demand for cellular telephones, coupled with the relatively high complexity and abundance of different cellular protocols, creates a particular need for an RF test set that can provide faster, more adaptable measurements.
The demand for cellular telephones worldwide has continued to increase dramatically and now exceeds 200 million subscribers. Fueling the demand are deregulation and privatization of the cellular telephone industry that have allowed for increased competition and a wider choice of services for the consumer. Developing countries that lack a modern telecommunications infrastructure are adopting cellular telephones at a rapid pace. At the same time, the existing base of subscribers are updating their cellular phones to take advantage of second generation digital cellular services. Multi-mode phones, capable of operating on multiple frequency bands and multiple cellular protocols, are now becoming popular to satisfy the coverage needs of roaming subscribers.
To meet the rising demand for cellular telephones, manufacturers have increased the number and capacity of their production lines. A critical process in any production line is the testing of each cellular phone which is typically performed by an RF test set. An RF test set is a measurement instrument that includes various stimulus and response components that operate both to control the operation of the cellular phone and to perform parametric measurements of the cellular phone according to a selected set of radio tests. Stimulus components of the RF test set generally include an RF signal source and an audio source. A response measurement component of the RF test set is generally an RF receiver in the form of a down-converter and demodulator. The RF test set must generally be capable of emulating a cellular base station using established cellular protocols and performing radio tests of the cellular telephone.
FIG. 1 illustrates the process of assembling and testing a cellular phone in a typical production line. A cellular phone 16 is tested at different points in the production process. The printed circuit assembly (PCA) is tested in a pre-test operation 10 for functionality after loading the electronic components. After being fully assembled, a series of final tests are performed to test the cellular telephone 16 for functionality. The proper operation of the cellular phone display is verified during a visual operation 12 and the proper operation of the keypad is verified during a keypad operation 14. The visual operation 12 and keypad operation 14 can be performed manually or by using automated systems.
A series of radio tests are then conducted using an RF test set 20 which simulates a cellular base station to communicate with the cellular phone 16 while measuring its performance against specification limits during a selected set of radio tests 18. Because the radio tests 18 tend to be slow and complex, the production line capacity may be limited by the throughput of the RF test set 20.
Prior art RF test sets such as the HP 8922 perform radio tests in a sequential fashion, one test followed by another test, until the selected set of radio tests 18 is completed. Radio tests for cellular telephones traditionally involve complex parametric measurements for both the transmitter and the receiver. Transmitter tests typically include modulation accuracy, transmitter power, output RF spectrum, and power versus time. Receiver tests may include receive sensitivity and bit error rate. Each radio test requires conducting call processing operations to control the cellular phone 16 using cellular protocols, then making measurements of the parameters of interest according to each radio test, and finally processing the measurements to obtain the results for each radio test.
Using sequential testing methods according to the prior art, the total time for the selected set of radio tests 18 for each cellular phone 16 is on the order of 35 to 90 seconds. Because this total time can limit the throughput of the production line, the traditional solution has been to purchase multiple RF test sets to add test capacity which substantially adds to the manufacturer""s production line cost and complexity. It would therefore be desirable to provide an RF test set with a concurrent measurement architecture to obtain increased measurement throughput and faster radio test times.
In accordance with the present invention, an RF test set having a concurrent measurement architecture is provided. The RF test set is adapted for testing an RF device such as a cellular phone according to a set of RF tests. An RF source and an RF receiver are used to communicate with the cellular phone in order to perform the call processing operations to control the cellular phone while performing concurrent measurements according to the RF tests. Concurrent measurements allow simultaneous operation of concurrent measurement processes and call processing operations to take place in the RF test set in order to decrease the total time required for each RF test and to increase measurement throughput of the RF test set.
The measurement architecture of the RF test set is organized into three layers; a user interface layer, a virtual instrument layer, and a hardware interface layer. The user interface layer may contain a manual user interface to allow for manual operation of the RF test set via a display and front panel controls. A remote user interface allowing for connection of the RF test set to a computer allows for automating the radio tests.
The virtual instrument layer contains a set of virtual instruments each of which define a particular call processing or measurement function. Each virtual instrument may be invoked according to the requirements of particular radio test. In response, the virtual instrument calls upon the hardware resources such as RF sources and receivers to interact with the cellular phone and obtain measurement data. Multiple virtual instruments may be executing concurrently, along with multiple RF tests and call processing operations, to provide for substantial gains in measurement throughput.
One feature of the present invention is to provide an RF test set capable of concurrent measurements.
A further feature of the present invention is to provide an RF test set with a concurrent measurement architecture.
Another feature of the present invention is to provide an RF test set having concurrent measurements capable of simultaneous transmitter and receiver tests.
Another feature of the present invention is to provide an RF test set capable of conducting concurrent measurements according to a set of virtual instruments.